JP7219720B2 - electrochemical energy storage device - Google Patents

Description

The present invention relates to high-density electrical energy storage devices, preferably devices in which a liquid conductor (electrolyte) is in contact with a conductor (electrode) with a large surface area (preferably Porous carbon, folded graphene, etc.) relates to high density electrical energy storage devices based on the Helmholtz double layer effect.

An electric double-layer assembly usually consists of a negatively charged carbon composite electrode and a positively charged carbon composite electrode separated from each other by a separator having through porosity, while the active layers of both electrodes are microscopic. It is formed by a porous carbon or graphene layer and an electrode of a conductive current collector material.

A disadvantage of state-of-the-art capacitors is that they have a bottleneck or taper through which the current must pass in its path from the electrodes to the terminals outside the capacitor housing. Such unfavorable structures result in high internal resistance.

In order to overcome the current limitations in terms of current flow and internal resistance, the challenge was to devise an assembly of electrode current collectors with unprecedented dimensions and current flow optimization.

In a first aspect, the invention provides:
a housing (housing);
a first plurality of first electrodes;
a second plurality of second electrodes;
a separator between each pair of first and second electrodes;
A high-capacity capacitor comprising an electrolyte between the electrodes and in the separator,
A first plurality of first electrodes are at least substantially parallel planar conductors each connected at its edge to a first terminal, each first electrode extending from the first terminal to the first terminal. extending a predetermined first distance along one predetermined direction;
a second plurality of second electrodes are planar conductors at least substantially parallel to each other and to the first conductor and each connected at an edge thereof to a second terminal; one of the plurality of conductors is positioned between a first plurality of adjacent conductor pairs, each second electrode extending from the second terminal along a second predetermined direction along a predetermined second extend the distance of 2,
each of the first electrodes being connected to the first terminal over a distance exceeding the first distance;
each of the second electrodes is connected to the second terminal over a distance exceeding the second distance;
one side of the first terminal is exposed to the perimeter forming the outer surface of the housing;
One side of the second terminal relates to a bulk capacitor exposed to the periphery forming the exterior surface of the housing.

In this context, a bulk capacitor or energy storage device may be a device capable of storing a large amount of charge. Bulk capacitors may have a capacity greater than 100 kF, such as 250 kF, 500 kF, or more.

Capacitors typically comprise at least two electrodes in which charge can be stored and create an electric field between the electrodes. This charge can then be released again.

The capacitor comprises a first plurality of first electrodes and a second plurality of second electrodes. The first electrode is connected to the first terminal and the second electrode is connected to the second terminal.

Preferably, an individual first electrode extends between each pair of two adjacent second electrodes such that every other electrode is positioned.

A separator is preferably disposed between each pair of first and second electrodes. The separator, which could ideally be omitted, serves to ensure that the first electrode does not come into direct contact with the second electrode. The separator may preferably allow the electrolyte, or at least its ions, to pass through it.

As discussed below, the electrodes are preferably of the two-layer type, which is currently the most efficient type for capacitors.

The first and second electrodes are at least substantially parallel plate conductors. This parallel geometry ensures that the distance between adjacent electrodes is the same and can be made as small as possible for high efficiency and high capacity. This is normal for capacitors. Of course manufacturing non-uniformities and deviations can occur, but preferably the electrodes are as parallel as possible.

The flat plate shape is very thin, such as at least 5, but preferably at least 10, 20, 30 or less, compared to the longest dimension or even the shortest dimension in a plane perpendicular to the thickness direction of the electrode. A shape that has a shape with a thickness. In many cases, planar electrodes are flat or planar, but any shape can be used, such as bent or coiled shapes. Preferably, the electrodes have the same thickness throughout.

The first and second electrodes are each connected at one edge thereof to the first and second terminals, respectively.

The first electrodes each extend a first predetermined distance from the first terminal along a first predetermined direction, each of the first electrodes extending from the first electrode over a distance exceeding the first distance. connected to the terminal of The situation is the same for the second electrode.

In this context, the direction can be any direction, such as perpendicular to the side where the electrodes are connected to the terminals. The first and second directions can then be parallel and opposite.

In practice, the first and second distances may be the shortest distance from any portion of the first and second electrodes to the terminal.

Therefore, preferably the distance from the terminal to any part of the electrode is less than the distance at which the electrode is connected to the terminal. This distance is preferably defined by the contact surface between the terminal and the electrode and defined as the shortest path from there through the electrode to the location in question.

Therefore, the contact surface between the terminal and the electrode is large compared to the distance that charge must travel into the electrode. In this way fast charging is possible.

The present capacitor is therefore divided into multiple layers, each of the electrodes being insulated by separators and by extending the current collectors to the terminal connections, compared to known low-capacity wound capacitors. different in that.

In situations where the first and/or second electrodes are rectangular, the terminals are connected to the long sides of the electrodes along a portion of the side that exceeds the length of the other side of the rectangle, preferably the entire length. can be

Preferably, the first and second electrodes overlap when projected onto a plane parallel to one of the electrodes. This overlap is preferably at least, such as at least 50%, such as at least 60%, such as at least 60%, in a cross-section where one electrode (such as the first electrode) overlaps the surface of an adjacent electrode (such as the second electrode). As large as possible, such as 70%, such as at least 80%, such as at least 90%.

The capacitor has a housing and first and second opposing conductive surfaces, the first opposing conductive surface being connected to the first plurality of electrodes and the second opposing surface being connected to the second electrode. Connected to multiple electrodes. In practice, the first and second conductive surfaces are the surfaces of the actual first and second terminals.

The first and second terminals form an outer conductive surface of the housing. Thus, one side (inner side) of each terminal is connected to an electrode and the other side (outer side) of each terminal is exposed to the surroundings, thereby forming the outer surface of the housing. Thus, current can flow from the electrode across the thickness of the terminal to the conductive surface of the housing, resulting in low internal resistance.
In state-of-the-art capacitors, current must flow from the electrodes at least along the terminals to the connection points outside the housing. According to the invention, one side of each terminal is at least partially exposed to the environment. Preferably, one side of each terminal is completely exposed to the environment.

Preferably, the first and second terminals form opposing outer surfaces of the two housings. Accordingly, the capacitor of the present invention is preferably disposed within a housing with terminals exposed on two opposite surfaces. This has the advantage that the capacitors can easily be stacked in stacks to handle higher voltages or combined in parallel to achieve higher capacitance.

Preferably, the two largest surfaces of the housing can be formed by outer surfaces of the first and second second terminals. Preferably, these surfaces are the outermost surfaces so that the capacitors can be easily stacked to contact the electrodes of adjacent capacitors.

The first and second terminals have an overlapping area of at least 50%, more preferably at least 75%, especially at least 90% of the edge of the electrode to which the electrode is connected when projected onto a plane parallel to the terminals. respectively.

In a preferred embodiment, the first and second secondary terminals each have an overlapping area which, when projected onto a plane parallel to the terminals, has an area formed by the electrodes connected to the terminals. Preferably, said area of the terminals overlaps said area of the electrodes by at least 50%, more preferably by at least 75%, especially by at least 90%.

In a preferred embodiment, the first and second terminals have an area that, when projected onto a plane parallel to the terminals, does not exceed the area between the edges of the two outermost electrodes where the electrodes are connected inside the terminals. each have.

In a preferred embodiment, the first and second secondary terminals do not protrude from the outer edge of the remainder of the housing when projected onto a plane parallel to the terminals.

Preferably, the first and second conductive surfaces are not only exposed around the enclosure, but also extend farthest away from the center of the enclosure on their surfaces or sides, so that the two Capacitors may be stacked so that the first and second surfaces of one are in direct engagement with the other. At this time, capacitors can be easily stacked.

Preferably, the capacitor housing is box-shaped with two large-area opposing sides and four small-area sides, the two large-area opposing sides having or being constituted by conductive surfaces. be done.

Preferably, each of the first electrodes is connected to the first terminal over a distance greater than 1.5 times the first distance and each of the second electrodes is greater than 1.5 times the second distance. A second terminal is connected over a distance. This factor may be at least 2-fold, at least 3-fold, at least 4-fold, or at least 5-fold higher. The factor relates to the amount of charge given by a unit length of contact surface between the electrode and the terminal. The higher the factor, the lower the charge per same charge per same electrode area. Higher factors allow faster charging and see lower heat generation.

In some embodiments, the conductor is flat. This facilitates the manufacture of large capacitors.

Preferably, the first and second electrodes are directly attached to the first and second terminals respectively. This attachment or connection will transport charge to or from the electrode and is preferably of low resistance. Attachment may be direct fixation of the electrode to the terminal by press fit or by soldering/welding using a material with high conductivity having at least 50% of the conductivity of the electrode.

As mentioned above, preferably at least one electrode, but preferably all electrodes, comprises a bottom layer or current collector and a coating on two opposite sides of the bottom layer. Therefore, well-known two-layer technology can be used.

Preferably, the coating has a large surface area, such as when it comprises carbon and/or is constructed when it comprises nanotubes.

Preferably, the bottom layer consists of a conductive material such as aluminum.

Preferably, the electrolyte contains 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C ₈ H ₁₁ F ₆ N ₃ O ₄ S). In principle any conductive liquid such as water, salt water, etc. can be used.

Preferably, the separator is porous and may comprise, for example, PTFE having pores that allow electrolyte to pass through its interior.

Of course, the capacitor may be disposed in any type of housing, such as those known for PCB mounting capacitors for electronic equipment.

However, the present capacitor is primarily directed to a completely different area where very high capacitance is desired for a completely different purpose. The capacitor is sized to store power from the grid, e.g. when its frequency needs to be corrected, or when excess power is to be stored for later use. obtain. Therefore, the capacity and amount of charge to be stored is orders of magnitude greater than what is produced for conventional capacitors. Capacitances on the order of 0.5 MF to 1 MF or even higher are envisioned, whereby the capacitor itself will have a size or volume ^{of 10-15 kcm 3 (} 10-15 L) or larger.

As will be explained below, the physical sign of the surface can be given because the capacitors can be polarized, so how the capacitors are connected together becomes important.

Preferred embodiments are described below with reference to the drawings.

1 is a diagram of a prior art bulk capacitor; FIG. 1 is a diagram of a large capacitor (enclosure only partially shown) according to the invention; FIG. 3 is a diagram of the dimensions of the electrodes used in the capacitor of FIG. 2; FIG. 3 is a side view of the capacitor of FIG. 2 including the housing; FIG. FIG. 4 is a top view of the capacitor;

FIG. 1 shows a prior art bulk capacitor having several first and second electrodes, the first electrode 12 and second electrode 16 of which are shown. The electrodes are arranged in a parallel fashion, all first electrodes being connected to a first terminal 14 and all second electrodes being connected to a second terminal 18 . Typically, to obtain higher capacity (surface area), a liquid electrolyte is provided between the electrodes and a separator material (not shown) is disposed between each adjacent pair of electrodes.

Connections are made via thin stretches of electrode material (at the top). A problem seen with this design is that the charge borne on the electrode must travel through a narrow extension of the electrode in order to be available at the terminal. This narrow stretch creates a bottleneck and increases internal resistance and hence heat generation during fast charging and discharging. Furthermore, narrow stretches generally limit fast charge/discharge rates.

In FIG. 2, a capacitor 20 according to the invention is shown, the circle component being enlarged to show the internal structure. Components of the capacitor housing are not shown for a better understanding of the structural details. However, first terminal 24 and second terminal 28, which form the outer conductive surface of the housing, are shown. The first and second terminals 24, 28 form two opposing surfaces of the capacitor housing.

Additionally, the first and second electrodes are arranged in an alternating parallel configuration. Additionally, separators 27 are disposed between each pair of adjacent electrodes, and a liquid electrolyte is provided between the electrodes and within the separators.

A first electrode 22 is attached to a first terminal 24 and a second electrode 26 is attached to a second terminal 28 .

However, the electrodes are then attached directly to the terminals along their sides so that charge is supplied directly from the terminals to the electrodes.

In fact, looking at FIG. 3, the electrodes 22, 26 are preferably square, attached directly to the terminal (upper bold line), and have a width W along the edge attached to the terminal, which is longer than the length L, which is the length away from the terminal perpendicular to it.

With this structure, the charge supplied to the electrode is supplied to it over a large area, thereby keeping the resistance low. In addition, the distance that charge must travel is kept as short as possible, thereby further minimizing resistance and keeping heat generation to a minimum, while optimizing charge and discharge times.

Dimensions can directly affect the parameters of the capacitor. The length indicates the distance the charge has to travel, hence the charging and discharging time as well as the resistance and heat generation, while the width indicates the overall capacitance of the capacitor.

Preferably, the electrode comprises an inner layer, a current collector, its coating and an electrode material.

A preferred current collector is made from aluminum as it has high conductivity while being inexpensive and lightweight. However, other conductors such as copper, gold and silver can also be used. Essentially any conductive element or composites thereof can be used.

Preferred electrodes are based on carbon-based materials with large surface areas, such as materials containing porous carbon and especially nanotubes. Other conductive materials such as silicon-based materials or composites with metals may be used.

A currently preferred electrolyte is 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C ₈ H ₁₁ F ₆ N ₃ O ₄ S ₂ ). Generally, aqueous electrolytes are fast but have low decomposition voltages, while organic electrolytes are slow but have high decomposition voltages. Naturally, a fast electrolyte with a high decomposition voltage is desired.

An alternative electrolyte is tetraethylammonium tetrafluoroborate (TEABF ₄ )(C ₈ H ₂₀ BF ₄ N)-(C ₂ H ₅ ) ₄ N in either propylene carbonate (PC) or acetonitrile (AN) It can be a common organic electrolyte such as ( _BF4 ). Common aqueous _electrolytes include KOH and _H2SO4 .

A currently preferred separator is a membrane material based on PTFE. Preferably, the separator is chemically inert and has customizable pore size and pore distribution.

Alternative separator materials can be paper, cloth, or customized plastics. Essentially any material can be used as long as it has pores large enough to allow the electrolyte to pass through.

The capacitor is particularly suitable for use with very large charges and is therefore suitable for very large capacities. Capacities on the order of 0.5 MF to 1 MF are envisioned, which would give the capacitor itself a size or volume of 10,000 cm ³ to 15,000 cm ³ (10-15 L). Therefore, the present capacitor can be used in very different situations than a small capacitor mounted on a PCB.

The capacitor is disposed within a housing (see FIGS. 4 and 5), with terminals 24, 28 forming the outer conductive surfaces of the housing. Preferably, the terminals 24, 28 are exposed on two opposing surfaces so that the capacitor can be easily stacked in stacks to allow it to handle higher voltages, or more Can be combined in parallel to achieve high capacity.

Thus, the two largest surfaces of housing 30 may be formed by components connected to the outer surfaces of terminals 24, 28 or electrodes. Housing 30 is preferably a box-shaped housing.
Preferably, these surfaces are the outermost surfaces so that the capacitors can be simply stacked to contact the electrodes of adjacent capacitors. The first and second terminals 24,28 do not protrude from the outer edge of the remainder of the housing 30 when projected onto a plane parallel to the first and second terminals 24,28. When projected onto a plane parallel to the terminals, the first and second terminals 24, 28 are such that the electrodes are connected to the inside of the terminals and cover at least 50%, more preferably at least 75%, especially at least 75%, of said area of the electrodes. Each having an overlapping area of at least 50%, more preferably at least 75%, especially at least 90% of the edges of the electrodes, further having 90%.

In FIG. 5 the capacitor of FIG. 4 is shown from above. Therefore, the terminal 28 exposed to the surroundings, when projected onto a plane parallel to the terminal (

平面図）、端子の内側に接続される２つの最も外側の電極の縁部間の面積を超えない、面積を各々有する。

plan view), each having an area not exceeding the area between the edges of the two outermost electrodes connected inside the terminal.

Furthermore, since capacitors of this type are typically polarized, the protruding component 32 may be located on the side of the housing 30 with the terminals 28 forming the outer conductive surface. Corresponding accesses are provided on opposite sides (not shown) of housing 30 with terminals 24 forming a further outer conductive surface. Thus, the protruding component 32 can be arranged in one polarity to avoid connecting the oppositely polarized surface of another capacitor to the terminal 28 of the housing. This is a corrective attachment that ensures a simple physical encoding of the capacitor when stacking.
In addition, the present invention includes the following items.
[Item 1]
a housing;
a first plurality of first electrodes;
a second plurality of second electrodes;
a separator between each pair of first and second electrodes;
A high-capacity capacitor comprising an electrolyte between the electrodes and within the separator,
The first plurality of first electrodes are at least substantially parallel planar conductors each connected at its edge to a first terminal, each first electrode being connected to the first terminal. extends a first predetermined distance along a first predetermined direction from
said second plurality of second electrodes are planar conductors at least substantially parallel to each other and to said first conductor and each connected at its edge to a second terminal; One of said second plurality of conductors is positioned between said first plurality of adjacent pairs of conductors and each second electrode extends from said second terminal in a second predetermined direction. extending a predetermined second distance along, each of said first electrodes being connected to said first terminal for a distance exceeding said first distance;
each of the second electrodes being connected to the second terminal over a distance exceeding the second distance;
one side of the first terminal is exposed to a perimeter forming an outer surface of the housing;
one side of the second terminal is exposed to a perimeter forming an outer surface of the housing;
wherein the first and second electrodes are attached directly to the first and second terminals, respectively;
Each of said first and second terminals has an area that, when projected onto a plane parallel to said terminals, does not exceed the area between the edges of the two outermost electrodes to which said electrodes are connected inside said terminals. have and/or
One side of each terminal is completely exposed to the environment,
Large capacity capacitor.
[Item 2]
Each of said first and second terminals has an area that, when projected onto a plane parallel to said terminals, does not exceed the area between the edges of the two outermost electrodes to which said electrodes are connected inside said terminals. have, and
One side of each terminal is completely exposed to the environment,
A capacitor according to item 1.
[Item 3]
the first and second terminals form two opposing outer surfaces of the housing;
3. The capacitor according to item 1 or 2.
[Item 4]
When said first and second terminals are projected onto a plane parallel to said terminals, at least 50%, more preferably at least 75%, especially at least each having an area that overlaps by 90%,
A capacitor according to any one of items 1 to 3.
[Item 5]
wherein the electrodes are flat plates;
A capacitor according to any one of Items 1 to 4.
[Item 6]
Each of the first electrodes is connected to the first terminal over a distance that exceeds the first distance by 1.5 times, and each of the second electrodes extends the second distance by 1.5. connected to the second terminal over a distance of more than double;
A capacitor according to any one of Items 1 to 5.
[Item 7]
Each of the first electrodes is connected to the first terminal over a distance greater than twice the first distance, and each of the second electrodes is connected over a distance greater than twice the second distance. , connected to the second terminal;
A capacitor according to item 6.
[Item 8]
at least one electrode comprising a bottom layer and a coating on two opposite sides of said bottom layer;
A capacitor according to any one of Items 1 to 7.
[Item 9]
the coating has a large surface area;
9. Capacitor according to item 8.
[Item 10]
the bottom layer is made of a conductive material
10. Capacitor according to any one of items 8 or 9.
[Item 11]
the coating comprises carbon;
A capacitor according to any one of items 8 to 10.
[Item 12]
wherein the bottom layer comprises aluminum;
A capacitor according to any one of items 8 to 11.
[Item 13]
wherein the electrolytic solution contains 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C ₈ H ₁₁ F ₆ N ₃ O ₄ S ₂ );
A capacitor according to any one of items 1 to 12.
[Item 14]
the separator comprises PTFE with holes that allow the electrolyte to pass through it;
A capacitor according to any one of items 1 to 13.

Claims (14)

a housing;
a first plurality of first electrodes;
a second plurality of second electrodes;
a separator between each pair of first and second electrodes;
A high-capacity capacitor comprising an electrolyte between the electrodes and within the separator,
The first plurality of first electrodes are at least substantially parallel planar conductors each connected at its edge to a first terminal, each first electrode being connected to the first terminal. extends a first predetermined distance along a first predetermined direction from
said second plurality of second electrodes are planar conductors at least substantially parallel to each other and to said first conductor and each connected at its edge to a second terminal; One of said second plurality of conductors is positioned between said first plurality of adjacent pairs of conductors and each second electrode extends from said second terminal in a second predetermined direction. extending a predetermined second distance along, each of said first electrodes being connected to said first terminal for a distance exceeding said first distance;
each of the second electrodes being connected to the second terminal over a distance exceeding the second distance;
one side of the first terminal is exposed to a perimeter forming an outer surface of the housing;
one side of the second terminal is exposed to a perimeter forming an outer surface of the housing;
wherein the first and second electrodes are attached directly to the first and second terminals, respectively;
Each of said first and second terminals has an area that, when projected onto a plane parallel to said terminals, does not exceed the area between the edges of the two outermost electrodes to which said electrodes are connected inside said terminals. A large capacity capacitor. Each of said first and second terminals has an area that, when projected onto a plane parallel to said terminals, does not exceed the area between the edges of the two outermost electrodes to which said electrodes are connected inside said terminals. have, and
One side of each terminal is completely exposed to the environment,
A capacitor according to claim 1 . the first and second terminals form two opposing outer surfaces of the housing;
3. The capacitor according to claim 1 or 2 . said first and second terminals each have an overlapping area of at least 50 % of said edge of said electrode where said electrode is connected to said terminal when projected onto a plane parallel to said terminal;
A capacitor according to any one of claims 1 to 3. wherein the electrodes are flat plates;
A capacitor according to any one of claims 1 to 4. Each of the first electrodes is connected to the first terminal over a distance that exceeds the first distance by 1.5 times, and each of the second electrodes extends the second distance by 1.5. connected to the second terminal over a distance of more than double;
The capacitor according to any one of claims 1-5. Each of the first electrodes is connected to the first terminal over a distance greater than twice the first distance, and each of the second electrodes is connected over a distance greater than twice the second distance. , connected to the second terminal;
A capacitor according to claim 6 . at least one electrode comprising a bottom layer and a coating on two opposite sides of said bottom layer;
The capacitor according to any one of claims 1-7. the coating has a large surface area;
A capacitor according to claim 8 . 10. A capacitor according to any one of claims 8 or 9, wherein the bottom layer is made of a conductive material. the coating comprises carbon;
The capacitor according to any one of claims 8-10. wherein the bottom layer comprises aluminum;
The capacitor according to any one of claims 8-11. wherein the electrolytic solution contains 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C ₈ H ₁₁ F ₆ N ₃ O ₄ S ₂ );
The capacitor according to any one of claims 1-12. the separator comprises PTFE with holes that allow the electrolyte to pass through it;
The capacitor according to any one of claims 1-13.

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